Planetary gear pump

ABSTRACT

A pump wherein a central rotating gear drives flexible planet gears about its circumference and inside a circumferential ring gear shaped outer housing. The space between the central rotating gear and the circumferential ring gear varies in cross sectional area to form a pumping chamber and communicates with inlet and outlet ports to permit pumping of fluid therethrough. The variable shape of the pumping chamber is achieved through the use of non-concentric ring and sun gears, non-circular sun and ring gears, flexible segments in the ring gear, or a flexible sun gear.

United States Patent 1m Gondek 1451 Sept. 16, 1975 1 1 PLANETARY GEARPUMP [76] Inventor: John T. Gondek, Columbia Heights,

Minneapolis, Minn. 55421 1221 Filed: Nov. 21, 1973 21 1 Appl. No:417,765

Related US. Application Data [62] Division of Ser. No. 267,560, June 29,1972.

[52] US. Cl. 418/56; 418/153; 418/225 [51] Int. Cl F01c 5/04; FOlc 1/08[58] Field of Search 418/56, 156, 153, 227, 418/225 [56] ReferencesCited UNITED STATES PATENTS 2,731,919 1/1956 Prendcrgest 418/150 X3,039,398 6/1952 Michelis 418/153 .lepsen 418/153 Connelly 417/310Primary Examiner-C. .1. Husar Assistant Examiner-Richard E. Gluck [57]ABSTRACT A pump wherein a central rotating gear drives flexible planetgears about its circumference and inside a circumferential ring gearshaped outer housing. The space between the central rotating gear andthe circumferential ring gear varies in cross sectional area to form apumping chamber and communicates with inlet and outlet ports to permitpumping of fluid therethrough. The variable shape of the pumping chamberis achieved through the use of non-concentric ring and sun gears,non-circular sun and ring gears, flexible segments in the ring gear, ora flexible sun gear.

5 Claims, 13 Drawing Figures PATENTED SEP I 6 I975 szm 1 1; g

PLANETARY GEAR PUMP This is a division of application Ser. No. 267,560.flled June 29, I972.

BACKGROUND OF THE INVENTION Numerous types of pumps are known in theprior art. One class of pump which finds extensive utility in the fluidpumping art includes paddle pumps and sliding vane pumps. Paddle pumpsgenerally employ a rotating member with a number of flexible paddlesabout the circumference. This paddle assembly is rotated within agenerally circular housing which is non concentric with the paddleassembly so that the chamber between the rotating member and the housingvaries in cross section. The springy flexible paddles adjust to thisvariance and operate to pump fluid between ports which are incommunication with the chamber.

A number of difficulties are encountered with this type of pump. Sincethe paddles must be flexible to adjust to the varying width of thechamber they are easily deflected by higher pressure fluid so that thepumps must be limited to lower pressures. In addition. the continualrubbing of the paddles against the outside walls wears out the paddlesand requires a large driving force to overcome the friction. This largedriving force makes the pumps rather inefficient. Another difficultystems from the fact that the paddles tend to wipe dirt particles aroundthe outside of the chamber walls so that the chamber walls wear quicklyand soon develop a bypass.

Another type of pump is known as the sliding vane pump. These pumps havethe same offset central driving member positioned in a generallycircular housing but instead of flexible paddles they utilize comparartively rigid vanes which slide in and out of radial slots in the centraldriving member. The vanes are held against the outside wall by eithercentrifugal forces or spring forces. These type of pumps suffer many ofthe same disadvantages as discussed earlier. The vanes tend to wipe dirtparticles around the outside of the housing causing excessive wear. Alsothe vanes easily jam in the radial slots unless they are limited to usewith fluids which are. in themselves. good lubricants such as oil andthe like. The rubbing of the vanes against the outside walls requires alarge driving force making the pump inefficient and highly susceptibleto wear. The instant invention overcomes all of the above disadvantagesin a new and novel way as indicated below.

SUMMARY OF THE INVENTION Briefly. my invention contemplates using acentral rotational driving member that is provided with teeth about itscircumference. These teeth operate to rotate flexible planetary gearsabout the inside of a combination ring gear and housing. The centraldriving member can be thought of as a sun gear whereas the pumping gearsare referred to herein as planetary gears. Ports are formed in thehousing to communicate with the chamber between the sun gear and thering gear so that fluid may be pumped therethrough by the rotationalmotion of the planetary gears. In one embodiment the chamber dimensionsare caused to vary displacing the axis of the sun gear with respect tothe axis of the ring gear. In another embodiment the ring gear is madewith a changing radius and this radius can be varied repeatedly toprovide several pumps in a single planetary gear arrangement. Otherembodiments of the invention con template not only flexible planetarygears but flexible ring gears as well and also combinations of flexibleplanetary, sun and ring gears.

Since the planetary gears roll about the inside of the ring gear housingand about the outside of the central driving member or sun gear theytend to roll over dirt particles rather than dragging them along in anabrasive manner to wear parts of the pump. Obviously there is nodragging friction as with paddles or vanes but rather a rolling action.Accordingly much less force is neces sary to drive the pump and it istherefore much more efficient than prior art designs. Still anotheradvantage accrues from the fact that the planetary gears are held firmlyin place by virtue of their being geared to both the inside and outsidemembers so that relatively high fluid pressure can be generated in thepump. The more rigid the flexible gear is made the higher pressure thatcan be handled by the pump and several flexible gear designs areproposed herein which will achieve this end. Maintenance and repair ofthe pump are made easier since the flexible planetary gears may besimply slid in and out of the pump with very little effort. Prior artdesigns usually require that the entire central memher which carries thepaddles or vanes has to be re moved to permit repair. It may thereforebe seen that it is an object of my invention to provide a pump which ismore efficient. less costly for the pressures involved. easilymaintained. and less susceptible to wear.

Further objects and advantages will become apparent upon considerationof the following detailed descrip tion and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a view of one embodiment ofthe invention showing flexible planetary gears driven about the insideof a circumferential combination gear and housing by a sun gear.

FIGS. 2., 3 and 4 show various types of construction that may beemployed to produce the flexible planetary gears.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 1.

FIG. 6 is a schematic diagram showing a variation of the pump of FIG. 1wherein the outer circumferential housing or ring gear may comprise acircular member.

FIG. 7 shows another embodiment of my invention wherein the planetarygears are comparatively rigid and the ring gear has flexible portionstherein.

FIG. 8 is a sectional view taken on line 88 in FIG.

FIG. 9 shows a modification that may be made to the flexible portion ofFIG. 7 to provide improved flexibility.

FIG. I0 shows another embodiment of the present invention combining bothflexible planetary gears and flexible ring gear portions.

FIG. 11 is a sectional view taken along line Illl in FIG. 10.

FIG. I2 is a view of the opposite side of the pump of FIG. I0 showing inparticular the porting arrangement thereof.

FIG. 13 is a schematic diagram showing how the pump of FIG. I may beformed as a dual or balanced pump.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring simultaneously to FIG.I and FIG. one embodiment of the present invention is shown. A housingI0 is shown which has a pair of mounting feet I] and I2 formed thereonand an inside circumferential surface 13. Surface 13 is provided aboutits entire circumference with a series of teeth 32. Flexible planetarygears 26 are provided with a series of gear teeth 28 which engage teeth32 to permit rotation about the inner surface I3 of housing l0. Theflexible gears 26 are driven by a central driving member or sun gear 18which is rotated by a shaft 20 about an axis which is displaced withrespect to the nominal axis of housing 10. In the simplest configurationof my invention both the sun gear 18 and the housing may be madecircular as shown in FIG. 6. In FIG. 6 the surface 45 is a cylinderwhose axis is displaced slightly to the right of the axis of sun gear18. This embodiment is relatively inexpensive to produce since circularmembers are generally easy to machine. However. the embodiment of FIG. Iis designed to be somewhat more sophisticated than that of FIG. 6.

In FIG. 1 the pumping chamber is designated by the numeral IS. Pumpingchamber has a cross sectional area dependent upon the radius of sun gearI8 and the radius of surface 13 in housing 10. These two radii are keptconstant over the are defined as arc R in FIG. 1. Consequently. the sizeof chamber 15 throughout arc R is constant in cross section. On theopposite side of the pump the chamber is also constant in cross sectionthrough the are R; but the cross section is much smaller clue to thefact that a lesser radius is used for surface [3. The two differentradii surfaces 13 are smoothly connected together by ramp surfacesdesignated [7 and 19 which extend between the ends of arcs R and Myinvention will pump fluids if rotated in either direction. The prior artpumps, of course. can only operate in one direction due to the slant ofthe vanes or paddles. For the purposes of explanation the operation ofmy pump is explained with respect to clockwise rotation of sun gear 18.This clockwise rotation is transferred through gear teeth and gear teeth28 to a plurality of flexible planetary gears 26 which are therebycaused to roll along surface l3 in a clockwise direction. The gears 26themselves rotate in a counter clockwise fashion. With this direction ofrotation a port 37 at the top of FIG. I operates as an intake portdrawing fluid from a threaded intake opening 16 formed in housing [0. Aseach planetary gear 26 passes port 37 it is allowed to expand out due tothe increasing cross sectional area of chamber 15 caused by ramp 1).Thus. the space inside the planetary gear 26 and between the variousplanetary gears 26 increases in volume allowing fluid to enter fromintake port 37. This fluid is carried around the pump through theconstant cross sectional area of chamber 15 defined by arc R to outletport 38 which is connected to outlet opening 14. As the planetary gearsleave arc R they encounter ramp [7 and are squeezed down to thedimensions prevalent through arc R The squeezing action forces fluidfrom within flexible planetary gears 26 into exit port 38. The spacebetween the planetary gears is also decreased and fluid is forced fromthese spaces into exit port 38. Ports 37 and 38 are generally designedto be long enough so as to be in communication with all of the spaceswhich are being squeezed in the ramp areas between are R and are R Theends of the ports designated by numbers 25 and 27 are positioned so thatthey are slightly farther apart than the length of a squeezed downplanetary gear 26. This is to insure that the inlet and exit portscannot be in communication with either the space inside the planetarygear 26 or the space between two planetary gears 26 at the same instantof time. Such a situation would provide a by pass wherein fluid would beable to flow from the outlet port back to the inlet port.

In FIG. 5 it may be seen that shaft 20 is carried in a housing extension22. Sun gear 18 is shown press fitted on the shaft 20 although key waysor any other type of mounting may be used. In the preferred embodimentit is contemplated that sun gear 18 would comprise a hard rubbermaterial although metal and plastic would be equally suitable. The hardrubber sun gear 18 is molded with a small seal of softer material 23which generally protrudes slightly from the rest of gear 18. When gearI8 is closed into housing 10 and sealed by means of a cover 34 theprotruding sealing ring 23 is bent into a space 24 as shown in FIG. 5 soas to provide a good fluid seal. Other types of seals could be used aswell. Cover 34 is anchored to housing by means of a series of screws 35.Cover 34 may be made from plastic or metal or any other suitablematerial. In the preferred embodiment cover 34 is chosen to he of such athickness as to have a slight flexibility. This flexibility operates asa safety valve. If the pressure becomes too great inside pumping chamber15. cover 34 deflects slightly outward allowing the fluid to pass by theends of the planetary gears 26 and return to the inlet ports. Conscqucntly, no external or additional mechanism is re quired in the instantinvention to provide an over pressure safety release. Many types ofmaterials and forms of construction may be used for forming the flexibleplanetary gears 26. Two of these variations are shown in FIGS. 2, 3 and4.

In FIG. 2 one embodiment of a flexible planetary gear 26 is shown insection. The gear teeth are shown as gear teeth and they are formed bylaminating layers of metal 41, 42 and 43 together which metal comprisesany highly flexible metal such as spring steel. The teeth 40 are thensupported underneath by additional layers of spring steel 44 and 45which may comprise cylindrical members or portions of flat helicalsprings. Additional layers of springs or laminated material may be addedto provide a more rigid and more springy planetary gear 26 so thathigher pressures may be accommodated in the pumping chamber 15.

FIGS. 3 and 4 show another possible form of construction for flexibleplanetary gears 26. The teeth and the main body of the gear 49 may bemolded from a flexible hard rubber or plastic material. During themolding process several layers of reinforcing cords 51, 52 and 53 aremolded therein. These cords may comprise plastic fibers such as nylon.glass or rayon. For stiffer springs they may comprise metal wires. Inyet another arrangement reinforcing wires 51, 52 and 53 could compriseconcentric coil springs alternately wound in opposite directions whichcoil springs could be manufactured from spring steel for example. Across sectional view of this arrangement is shown in FIG. 4 wherein thesuccessive layers of coil springs are more visible. The embodiments ofFIGS. 2 and 3 are not the only ways the flexible planetary gears couldbe made. For low pressure pumps solid rubber could he molded into theshapes shown. Other embodiments could use flexible gears which have noopen space in the center at all but, on the contrary. are formed fromsolid rubber all the way to the core. Many other variations will occurto those skilled in the art and thus no limitation is intended by theshowings of FIGS. 2. 3 and 4.

In the embodiment of FIG. 1 there will be high pressure in the area ofexit port 38 on a rather continuous basis providing a one sided load onthe hearing 22 carrying shaft 20. To alleviate this problem. which couldbecome acute in higher pressure pumps, the design of FIG. 13 iscontemplated wherein a dual pump is provided so that the high pressureloads are balanced thus providing little or no sideways loading for thecentral shaft. FIG. 13 shows schematically only the geometry used inproviding the pumping chamber designated by the numerals 60. In theembodiment of FIG. 13, pumping chamber would be constant in crosssection during both of the arcs designated by R Chamber 60 would also beconstant in cross section but much smaller through the two arcsdesignated as R Ramp surfaces 6], 62, 63 and 64 would be used to connectthese arcs and provide the gradual change in chamber dimensions. If thepump were to be rotated in a clockwise direction, as viewed in FIG. 13,intake ports 65 and 66 would be positioned as shown and outlet ports 67and 68 would also be pictured as shown on opposite sides of therotational axis 69 of the sun gear. Since the high pressure areas are onopposite sides of axis 69 no unbalanced load is produced. All of theembodiments shown and discussed so far have employed flexible planetarygears. Another embodiment of the invention however uses generally rigidplanetary gears and incorporates flexible segments into the ring gear.Such an embodiment is disclosed in FIG. 7.

FIG. 7 shows schematically another embodiment of the invention with alayout similar to that of FIG. 1. As before, a shaft 70 rotates a sungear 71 inside a housing 72. Inlet and outlet ports 74 and 73communicate with inlet and outlet openings 75 and 76. Positioned withinhousing 72 is a ring gear comprising a generally rigid portion 77 and aflexible portion 78. The planetary gears 79 may be generally rigid inshape so as to compress into the soft portion 78 as shown on the left ofFIG. 7. Since soft portion 78 squeezes inward between planetary gears 79on the left, the cross sectional area of the pumping chamber 80 varies.Flexible portion 78 is thickest at point 81 and becomes progressivelynarrower in both directions until it abuts rigid portion 77 where thethickness is equal to the thickness of portion 77. It is contemplatedthat portion 78 will be molded originally so that the internal surface82 would have the same radius as the internal surface 83 of rigidportion 77. However. the outside surface of soft portion 78 designatedby the number 84 would extend outward to provide a thicker portionopposite point 81. As flexible portion 78 is inserted into housing 72 itwould be squeezed into the shape shown in FIG. 7. This form ofconstruction is used so that as planetary gears 79 rotate across themolded gear teeth on surface 82 surface 82 will more closely approximatethe shape at which they were molded since surface 82 will he pushed to aradius generally corresponding to its original position when molded. Inthis way it is assured that the teeth on planetary gears 79 will fitsnugly with the teeth on the inside of both ring gear portions 78 and77.

FIGS. 8 and 9 show more sophisticated versions of the pump of FIG. 7wherein the soft portion 78 is provided with a series of holes 85 whichextend through soft portion 78 so as to provide a multitude of voids orchambers therein. An arc shaped recess 87 is formed into the surface ofsoft portion 78 so as to connect togcther all of the holes 85 proximateto exit port 73. A second are shaped recess 88 is similarly formed inthe top half of soft portion 78 so as to connect together all oftheholes 85 proximate the inlet port 74. These re cesses 87 and 88 are thenconnected to their respective ports by means of a pair of passageways 89and 90. These passageways 89 and 90 permit fluids to pass in and out ofthe chambers formed by recesses 87 and 88 and the top cover 91 as shownin FIG. 8. Fluid can thus travel from recesses 87 and 88 into all of theholes 85. The fluid pressure thus introduced into the internal structureof soft portion 78 counter balances the fluid pressure in the pumpingchamber 80. This permits the st ft portion of the ring gear 78 to beconstructed from a material of less rigidity than would be the case ifsolid flexible material were used such as shown in FIG. 7. In theembodiment of FIG. 9 the planetary gears and the central sun gear havebeen eliminated so as to better show the position of the inlet and exitports and the recesses 87 and 88. However. upon assembly the geometrywould be the same as that of FIG. 7 and it can be seen that as thegenerally rigid planetary gears 79 pass across flexible portion 78 theywill squeeze down on the recesses 87 and 88 and on the voids or chambers85 squeezing fluid out through ports 89 and 90. However. the continuouspressure of fluid inside soft portion 78 will quickly return it to itsexpanded position wherever possible as. for example. between theplanetary gears. It should be noted that the soft portion of the ringgear in both the embodiments of FIG. 7 and FIG. 9 would probably beanchored to the outside casing by a suitable adhesive at the surface 84(as shown in FIG. 7) and at the surface 93 (as shown in FIG. 8].Adhesive would not be applied along the surface contiguous to cover 91or the surface on the side opposite the cover since this would hinderthe in and out radial flexing of the soft portion.

FIGS. 10, 11 and 12 show another embodiment of the present inventionusing a different type of porting arrangement and employing acombination of many of the principles discussed hereinabove. A housingcontains a ring gear comprising two relatively rigid con stant dimensionportions 107 and 108 and two flexible portions and 106 which couldincorporate any of the design features already discussed such as fluidfilled voids. Not only are portions of the ring gear flexible but alsothe planetary gears 104 are allowed to flex so that a double flexingaction as indicated in FIG. 10. In this embodiment the side loads on thedrive shaft 101 are reduced by making a dual or balanced pump arrangement. In addition maximum pumping is achieved by having both flexibleplanetary gears and flexible segments in the ring gear. For clockwiserotation of sun gear 102 the inlet ports would comprise ports H7 and 114whereas the outlet ports would comprise ports 115 and 116. As is evidentin FIG. 12 housing 100 is molded or cast to have two curved inlet andoutlet tubes num' hered 109 and respectively. Tube 109 would be indirect communication with inlet port 117 and swing across around shaftsupport 1]] to be in communica tion with inlet port 114. By a similardesign outlet port 116 would communicate with outlet tube H0 whichswings around shaft support 11] and underneath inlet tube 109 so as tocommunicate with outlet port US. It is clear that many othermodifications may be made to the invention as disclosed withoutdeparting from its spirit and scope of the novel features. Thus. thefollowing claims are presented to cover only these novel fea tures.

I claim:

1. A fluid pump comprising:

a generally cylindrical drive member adapted for rotation about its axisand having gear teeth about its circumference to form a sun gear;

a housing surrounding and supporting said drive member and having aflexible inner circumferential surface disposed at a varying distancefrom said generally cylindrical drive member so as to form a pumpingchamber therebetween said inner surface having gear teeth to form a ringgear;

inlet and outlet passageways in communication with said pumping chamber;

a plurality of flexible rolling members held between said drive memberand said inner circumferential surface adapted to be rolled by saiddrive member about said flexible inner surface and carry fluid throughsaid pumping chamber from said inlet ports to said outlet ports saidrolling members having gear teeth about their circumference to formplanetary gears.

2. The apparatus of claim 1 in which said inner surface has portions ofconstant radius about axes coincident with the axis of rotation of saidsun gear and ramp portions shaped to narrow said pumping chamber andconnect together the constant radius portions.

3. The apparatus of claim 2 in which there are a plurality of constantradius portions and a plurality ramp portions.

4. The apparatus of claim I in which said ring gear also has some rigidportions intermediate the flexible portions.

5. The apparatus of claim I in which said inlet and outlet passagewayscommunicate with the pumping chamber proximate said ramp portions.

1. A fluid pump comprising: a generally cylindrical drive member adaptedfor rotation about its axis and having gear teeth about itscircumference to form a sun gear; a housing surrounding and supportingsaid drive member and having a flexible inner circumferential surfacedisposed at a varying distance from said generally cylindrical drivemember so as to form a pumping chamber therebetween said inner surfacehaving gear teeth to form a ring gear; inlet and outlet passageways incommunication with said pumping chamber; a plurality of flexible rollingmembers held between said drive member and said inner circumferentialsurface adapted to be rolled by said drive member about said flexibleinner surface and carry fluid through said pumping chamber from saidinlet ports to said outlet ports said rolling members having gear teethabout their circumference to form planetary gears.
 2. The apparatus ofclaim 1 in which said inner surface has portions of constant radiusabout axes coincident with the axis of rotation of said sun gear andramp portions shaped to narrow said pumping chamber and connect togetherthe constant radius portions.
 3. The apparatus of claim 2 in which thereare a plurality of constant radius portions and a plurality rampportions.
 4. The apparatus of claim 1 in which said ring gear also hassome rigid portions intermediate the flexible portions.
 5. The apparatusof claim 1 in which said inlet and outlet passageways communicate withthe pumping chamber proximate said ramp portions.